Electron discharge device of the magnetron type



Dec. 3, 1946. B N 2,411,953

ELECTRON DISCHARGE DEVICE OF THE MAGNETRON TYPE Filed Jan. 10, 1944 I I N /2 a 2 a 3 l0 9 a film/rm. Mama 6: 40m! Patented Dec. 3,1946

umrso STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE OF THE MAGNETRON TYPE William C. Brown, Watertown, Mass, 'assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application January 10, 1944, Serial No. 517,756

8 Claims. (Cl. 315-) I type of outputcoupling devices-with the result .that such devices have been relatively less efelectrodes at a plurality of points whereby energy 'may be fed from each of said points directly into said common cavity resonator.

Another object is to eliminate the tendency of the oscillator to generate spurious oscillations whereby substantially all of the oscillating energy is concentrated in the, desired wave length.

The foregoing and other objects of this invention will be best understood from the following description of an exempliflcation thereof, reference being had to the accompanyi drawing wherein:

Fig. 1 is a vertical cross-section of an arrangement constructedin accordance withmy invention; and

Fig. 2 is a cross-section taken along line 2-2 of Fig. 1.

The magnetron illustrated in the drawing comprises a casing l consisting of an outer cylinder 2, an inner cylinder 3. a bottom annular wall member 4, and a top annular wall member 5.

The above members are preferably made of highr ly conductive material, such as copper, and are soldered together so as to form a hermetically sealed annular discharge chamber. Within the discharge chamber the upper surface of the bottom wall member 4 supports a plurality of anode elements 6, the upper faces of which are adapted to receive electrons emitted from the emitting surfaces of a cathode l. The anode elements 6 are likewise formed'of highly conductive material, such as copper, and are spaced from each other to provide intervening cavity resonators each of which is resonant to the desired output frequency.

The cathode I may be of the indirectly heated thermionic type comprising a hollow annular cathode member 8 formed of suitable conducting material, such as nickel, and coated on its lower A surface with suitable electron emitting oxides. Within the member 8 is supported a heater filament 9. Shielding members l0 may be provided extending from opposite sides of the cathode emitting surface to preventelectrons from passing into regions other than the cathode-anode discharge space. A lead-in conductor II is connected to the hollow member 8. One end of the heater 9 is also electrically connected to the member 8,'the other end of said heater being connected to a lead-in conductor l2 which is suitably insulated from the member 8. The heater 9 may be suitably coated with insulating material so as to prevent electric contact with the member 8, except as above indicated. The lead-in conductors II and I! extend through pipes l3 hermetically sealed through the top member 5. Said lead-in conductors also pass out through glass seals l4 carried at the outer ends of said pipes Hi.

In order to generatea large amount of power a large number of anode elements 6 are provided.

Sixty such elements are utilized in the embodiment shown in the drawing. Although such an arrangement might be capable of operating in various modes, each of which produces a different frequency of oscillation, the desired mode of oscillation is that in which alternate anode elements are of opposite voltage phase. Thus, at each instant thirty complete Wave lengths of the oscillations would exist around the anode structure. In order to couple the generated energy into an output device, a plurality of coupling conductors ii are connected to predetermined anode elements 6 and extend through openings IS in the bottom wall member 4 into a common The cavity resonator l1 II in the proper way, said probes ii are spaced wave length can be adjusted-to the spacing be-- tween the probes l within certain limits. Also'" in order for the probes llto feed energy into the cavit resonator II in the proper way, each said probes I5 should be of the same voltage phase. By spacing the probes ll an even number of anode elements apart it will be seen that the above condition is satisfied particularly when the device is oscillating in the desired mode as above described. Thus in the embodiment illus trated in the drawing the probes l5 are'spaced twelve anode elements apart.

The energy which is propagated through the cavity resonator I1 is led off by means of a suitable loop l8, one end of which is electricallyconnected to a pipe 19 hermetically sealed through a side wall of the cavity resonator I]. The other end of said coupling loop 18 extends through said pipe [9 and passes out through a glass seal 20 carried at the outer end of said pipe l9.--

A magnet 2| provides the magnetic field for the magnetron. This magnet is formed with a central circular pole piece 22 and an outer annular pole piece 23 concentrically disposed with respect to the pole piece 22. In this way a radial magnetic field is created transverse to the discharge path between the cathode 1 and the anode elements 6. The magnet 2| is cut away at 24 in order to allow the pipe 19 and its seal 20 to project therethrough, while the pole pieces 22' and 23 may be attached separately to allow for ready assembly of the tube with the magnet structure.

In such an arrangement as described above, the energy which is generated within each cavity resonator between adjacent anode elements 8 is readily propagated through a relatively short distance to a probe l5 and thus is eflectively and" efllciently transferred into the common cavity resonator i1, and thus into the output. In addition, the presence of the common cavity resonator ll has a frequency stabilizing effect upon the entire device and tends to cause the tube to oscillate only in the desired mode described above, other undesired modes tending to be suppressed. Thus oscillators built in accordance with my invention can deliver large amounts of powerin an cilicient and efiective manner.

Of course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. An electron-discharge device comprising: an envelope enclosing a cathode and an anode structure; said anode structure including a plurality of anode elements forming a plurality of cavity resonators each of which is adapted to resonate at a predetermined output frequency; a common cavity resonator adapted to resonate at said pre= determined output frequency; and a plurality of spaced probe electrodes projecting into said com mon cavity resonator; said probe electrodes being connected, respectively, to anode elements which are spaced-from each other by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency.

2. An electron-mscharge device comprising: an

1 equal to an integral number determined output frequency;

envelope enclosing a cathode and an anode structure; said anode structure including a plurality of anode elements forming a plurality of cavity resonators each of-which is adapted to resonate at a predetermined output frequency; a common cavity resonator adapted to resonate at said prea plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements which are spaced from each other by a distance of wave lengthsjcorresponding to said predetermined output frequency; and output means coupled to said common cavity resonator.-

3. An electron-discharge device comprising: an envelope enclosing a cathode and an anode structure; said anode structure including a plurality of anode elements forming a plurality of cavity resonators each of which is adapted to resonate at a predetermined output frequency; a common cavity resonator adapted to resonate at said predetermined output frequency; and a plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements, which are spaced from each other by an even number of the same and by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency.

4. An electron-discharge device comprising: an envelope enclosing a cathode and an anode structure; said anode structure including an even number of circularly-disposed anode elements forming an even number of cavity resonators eachof which is adapted to resonate at a. predetermined output frequency; a common cavity resonator adapted to resonate at saidpredetermined output frequency; and a plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements-which are spaced from each other by an even number of the same and by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency.

5. A magnetron comprising: an envelope enclosing a cathode and an anode structure; said anode structure including a plurality of anode elements forming a plurality of cavity resonators each of which is adapted to resonate at a predetermined output frequency; onator adapted to resonate output frequency;

a common cavity resat said predetermined a plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements which are spaced from each other by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency; and means adrespectively, to anode elements which are spaced from each other by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency; output means coupled to said common cavity resonator; and means adjacent said cathode and said anode structure for producing a magnetic field transverse to the discharge path therebetween.

'7. A magnetron comprising: an envelope enclosing a cathode and an anode structure; said anode structure including a plurality of anode elements forming a plurality of cavity resonators each of which is adapted to resonate at a predetermined output frequency; a common cavity resonator adapted to resonate at said predetermined output frequency; a plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements which are spaced from each other by an even number of the sameand by a distance equal to an integral number of wave lengths corresponding to said predetermined output frequency; output means coupled to said common cavity resonator; and means adjacent said cathode and said anode structure for producing a magnetic field transverse to the discharge path therebetween.

8. A magnetron comprising: an envelope enclosing a cathode and an anode structure; said anode structure including an even number of circularly-disposed anode elements forming an even number of cavity resonators each of which is adapted to resonate at a predetermined output frequency; a common cavity resonator adapted .to resonate at said predetermined output frequency; a plurality of spaced probe electrodes projecting into said common cavity resonator; said probe electrodes being connected, respectively, to anode elements which are spaced from each other by an even number of the same and by a distance equal to an integral number of Wave lengths corresponding to said predetermined output frequency; and means adjacent said cathode and said anode structure for producing a magnetic field transverse to the discharge path therebetween.

WILLIAM 0. BROWN. 

